A girl is vaccinated against HPV in a file photo. Women who have been vaccinated with the HPV (human papillomavirus) vaccine also need to be screened because the shots do not protect against all forms of the virus.

OTTAWA – Doctors should stop ordering yearly Pap tests for most women, and routine screening for cervical cancer in younger women should be abandoned altogether, a federal task force is recommending.

For the first time in nearly 20 years, the Canadian Task Force on Preventive Health Care has released an updated guideline for cervical cancer screening that recommends starting screening when women are older, and screening them less often in order to avoid the harms of excessive testing.

Published Monday in the Canadian Medical Association Journal, the new guideline recommends that women aged 25 to 69 without symptoms of cervical cancer who are, or who have ever been, sexually active, be screened once every three years with a Pap test, which detects abnormal cells in the cervix.

The 1994 guideline recommended screening every three years, but only after two consecutive negative Pap test results.

The old guideline also recommended Pap smears for women once they turn 18 or become sexually active.

But the task force says it could find no benefit to outweigh the potential harms of screening women under 25.

Nearly half — 42 per cent — of women aged 18 to 19 have reported being screened at least once within the previous three years, the authors write in the CMAJ. But the incidence of cervical cancer in women less than 20 is low (0.2 cases per 100,000) and no deaths from cervical cancer were reported among Canadian women under 20 between 2002 and 2006.

Neither could the task force find any data to support the argument that screening younger women helps prevent deaths from cervical cancer when they’re older. The risk of cervical cancer increases after age 25, and peaks in a woman’s 50s.

Younger women are more likely to have abnormal Pap results. A substantial proportion will have “false positive” results, leading to unnecessary and invasive treatments for abnormalities that would never progress to cancer — procedures that can cause pain, bleeding and irreversible damage to the cervix that can jeopardize a woman’s chances of carrying a future pregnancy.

Over the past 50 years, deaths due to cervical cancer have fallen dramatically, the panel writes. Today, a woman’s risk of dying from the disease is 0.2 per cent.

“It is likely that much of the change seen in the incidence of cervical cancer in Canada is due to screening, but early and frequent (often annual) cervical screening is unnecessary: other countries have achieved similar outcomes with less frequent testing and starting screening at older ages,” the panel reports.

“The American have said very specifically, no woman should have annual Pap testing,” said Dr. James Dickinson, a member of the task force and chair of the guideline-working group.

“Cervical cancer was, and still is a horrible disease to get. It spreads right through the whole of a woman’s pelvis and causes horrible problems with bowel and bladder. It can be a truly horrible disease,” said Dickinson, a professor of family medicine and community health sciences at the University of Calgary.

Without Pap testing, the disease would affect 1.5 per cent of women. “This is the most successful screening test that we have available,” Dickinson said. “It really can reduce the disease by more than 80 per cent, 90 per cent, and that’s fantastic.”

Expert advisory bodies have for several years been recommending doctors do away with annual Pap testing and instead screen every three years. “It’s just that (doctors) and women have got into this habit of annual Pap smears, and we’d like to get them out of that habit,” he said.

“The evidence says that three years is enough to get the benefits.”

Some women do need more frequent screening, including those who have HIV or are immune suppressed.

Overall, for younger women, “We said look, this disease is almost non-existent in women under the age of 20, so we really should not do it for women under 20,” Dickinson said. “Even for women between 20 and 25, it’s extremely rare.”

“The test doesn’t work very well for the sorts of cancers that seem to develop between the age of 20 and 24,” he added.

“On balance, we say that under (the age of) 25, it’s not worth doing.”

For women aged 25 to 29, the panel recommends screening every three years. But they’ve assigned it a “weak” recommendation, because of their concerns about the rate of false-positives and the harms of over-treatment. “Although most women would want to follow the recommended course of action, many would not.” Women in this age group should discuss the potential risks and benefits with their doctor, they said.

Over the age of 30, the risks of cervical cancer are substantially higher, Dickinson said. “Between 30 and 69, we strongly advise screening” every three years, he said.

Screening can stop in women at age 70 and older after three successive negative Pap test results in the last 10 years, according to the new guideline.

The Canadian Cancer Society currently recommends women have regular Pap tests starting by age 21 if they’re sexually active.

In light of the new guideline, the organization says it will consult with cervical cancer screening experts across the country to determine “whether this is something we should consider changing,” said Gillian Bromfield, director of cancer control policy. She said most provincial and territorial cancer agencies recommend screening starting at age 21.

“There’s some controversy around whether we really have enough information to make this call,” she said. “We don’t have enough evidence to conclude whether we’ve got a really strong benefit in these younger women … or if we have no benefit at all.”

Bromfield said women should continue to be screened even if they’re no longer sexually active. Women who have been vaccinated with the HPV (human papillomavirus) vaccine also need to be screened because the shots do not protect against all forms of the virus.

In 2012, an estimated 1,350 new cases of cervical cancer were diagnosed in Canada, with about 400 deaths.

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